Patterned and switchable surfaces for biomaterial applications

Chapter 5 – Surface plasmon resonance imaging of polymer microarraysThis approach was conducted for a larger polymer array consisting of PAA, PEI,and PLL (for structures see Figure 4.3B-D) spotted at concentrations of 2.0, 1.0, 0.5,0.25, 0.1, 0.05 and 0.01 mg/ml, resulting in an array of 21 polymer spots of variedthickness and refractive index. Similar to the experiment described above, this arraywas first equilibrated in phosphate buffer and the reflectivity for a range of angles ofincidence was measured for each spot. Then a fixed angle experiment at 48.9° wasconducted to monitor the change in SPR signal intensity versus time for the exchangeof phosphate buffer with 1% ethanol. The resultant sensorgram is shown as Figure5.12A. Subsequently, the measurement of reflectivity for a range of angles ofincidence was repeated after ethanol injection and the measured change in theresonance angle was used to convert the change in SPR signal intensity measured forthe fixed angle experiment (Figure 5.12A) to a change in resonance angle againsttime, shown as Figure 5.12B. Significantly, the resultant shift in resonance anglemeasured for the majority of spots converged to -0.141° as expected. Only four spotsdiffered significantly from the expected value, which had thicknesses greater than 15nm.5-186